Issue2033 contrast minimum understanding

[bruce-usab]

Closes issue #2033

Preview understanding doc

[bruce-usab]

Current:

The intent of this Success Criterion is to provide enough contrast between text and its background so that it can be read by people with moderately low vision (who do not use contrast-enhancing assistive technology). For people without color deficiencies, hue and saturation have minimal or no effect on legibility as assessed by reading performance (Knoblauch et al., 1991). Color deficiencies can affect luminance contrast somewhat. Therefore, in the recommendation, the contrast is calculated in such a way that color is not a key factor so that people who have a color vision deficit will also have adequate contrast between the text and the background.

Proposed:

The intent of this Success Criterion is to provide enough luminance contrast between text and its background so that it can be read by people with moderately impaired contrast perception, without the use of contrast-enhancing assistive technology.

For people with Color Vision Deficiencies (CVD), often referred to as "color blindness", hue and saturation have minimal or no effect on legibility as assessed by reading performance (Knoblauch et al., 1991). Further, CVD per se, do not negatively affect luminance contrast perception (Márta Janáky et al., 2013; Cagri Ilhan et al., 2018). For people with color deficiencies, luminance contrast has a significant impact on legibility. Therefore, in the recommendation, contrast is calculated in such a way that color (hue) is not a key factor. People with other types of low vision also require strong contrast between text and its background for fluid reading.

[bruce-usab]

Ping to @Myndex — I think additional information and detail about variants of 'color blindness' could/should be an addition issue/PR.

[Myndex]

Hi @bruce-usab

This is good. I have a suggestion on the last couple sentences:

Instead of:

...For people with color deficiencies, luminance contrast has a significant impact on legibility. Therefore, in the recommendation, contrast is calculated in such a way that color (hue) is not a key factor. People with other types of low vision also require strong contrast between text and its background for fluid reading...

I would suggest:

... For all users of visual content, adequate luminance contrast is needed between text and its background for good readability. Many different visual impairments can substantially impact contrast sensitivity, requiring more luminance contrast, regardless of color (hue). Therefore, in the recommendation, contrast is calculated in such a way that color is not a key factor.

---

Errata:

In the second paragraph of the proposed:

...Further, CVD per se, do not negatively affect l...

should probably be

...Further, CVD per se, does not negatively affect l...

---

As for additions, I could see another PR to add in:

1. Very saturated reds, oranges, blues, and purples are inherently low in luminance, and therefore should generally be the darkest of two colors.

2. Some color-insensitive vision types see colors that have a substantial red component as visually much darker, emphasizing the importance of num 1.

3. While readability relies on luminance contrast, essentially disregarding color(hue), this is not to say that color is not valuable for other visual tasks such as categorizing, object recognition, or differentiating lines on a map. Those with color-insensitive vision are at a disadvantage for tasks like these, see 1.4.1

[bruce-usab]

Thanks @Myndex ! I took your suggestions, which made be realize I could replace with CVD with its definition.

Yes, I agree your 1/2/3 could/should be a separate issue and PR.

[bruce-usab]

Current:

The intent of this Success Criterion is to provide enough contrast between text and its background so that it can be read by people with moderately low vision (who do not use contrast-enhancing assistive technology). For people without color deficiencies, hue and saturation have minimal or no effect on legibility as assessed by reading performance (Knoblauch et al., 1991). Color deficiencies can affect luminance contrast somewhat. Therefore, in the recommendation, the contrast is calculated in such a way that color is not a key factor so that people who have a color vision deficit will also have adequate contrast between the text and the background.

Proposed:

The intent of this Success Criterion is to provide enough luminance contrast between text and its background, so that it can be read by people with moderately low vision or impaired contrast perception, without the use of contrast-enhancing assistive technology.

For all consumers of visual content, adequate luminance contrast is needed between text and its background for good readability. Many different visual impairments can substantially impact contrast sensitivity, requiring more luminance contrast, regardless of color (hue). For people who are not able to distinguish certain shades of color — often referred to as color blindness — hue and saturation have minimal or no effect on legibility as assessed by reading performance (Knoblauch et al., 1991). Further, the inability to distinguish certain shades of color does not negatively affect luminance contrast perception (Márta Janáky et al., 2013; Cagri Ilhan et al., 2018). Therefore, in the recommendation, contrast is calculated in such a way that color (hue) is not a key factor.

[Myndex]

Yes, I agree your 1/2/3 could/should be a separate issue and PR.

Thank you @bruce-usab … do you think these adds should be inside a green “note” or just a couple paragraphs?

[bruce-usab]

@Myndex -- I don't think Understanding uses green notes. So I think the information can be added as stand-alone paragraph(s).

[bruce-usab]

Today I inserted low vision or into intent sentence of this PR, in response to issue comment from @GreggVan.

[GreggVan]

+1 to removing "luminance" from in front of contrast

…

On Aug 22, 2023, at 6:43 AM, Mike Gower ***@***.***> wrote: @mbgower commented on this pull request. In understanding/20/contrast-minimum.html <#3284 (comment)>: > @@ -11,14 +11,13 @@ <h1>Understanding Contrast (Minimum)</h1> <section id="intent"> <h2>Intent of Contrast (Minimum)</h2> - <p>The intent of this Success Criterion is to provide enough contrast between text and - its background so that it can be read by people with moderately low vision (who do - not use contrast-enhancing assistive technology). For people without color deficiencies, - hue and saturation have minimal or no effect on legibility as assessed by reading - performance (Knoblauch et al., 1991). Color deficiencies can affect luminance contrast - somewhat. Therefore, in the recommendation, the contrast is calculated in such a way - that color is not a key factor so that people who have a color vision deficit will - also have adequate contrast between the text and the background. + <p>The intent of this Success Criterion is to provide enough luminance contrast between text and its background, so that it can be read by people with moderately low vision or impaired contrast perception, without the use of contrast-enhancing assistive technology. + </p> + <p>For all consumers of visual content, adequate luminance contrast is needed between text and its background for good readability. + Many different visual impairments can substantially impact contrast sensitivity, requiring more luminance contrast, regardless of color (hue). + For people who are not able to distinguish certain shades of color &mdash; often referred to as <q>color blindness</q> &mdash; hue and saturation have minimal or no effect on legibility as assessed by reading performance (<a href="https://doi.org/10.1364/JOSAA.8.000428" title="Effects of chromatic and luminance contrast on reading">Knoblauch et al., 1991</a>). + Further, the inability to distinguish certain shades of color does not negatively affect luminance contrast perception (<a href="https://pubmed.ncbi.nlm.nih.gov/24103453/" title="Achromatic luminance contrast sensitivity in X-linked color-deficient observers: an addition to the debate">Márta Janáky et al., 2013</a>; <a href="https://link.springer.com/article/10.1007/s10792-018-0881-7" title="Contrast sensitivity of patients with congenital color vision deficiency">Cagri Ilhan et al., 2018</a>). ⬇️ Suggested change - Further, the inability to distinguish certain shades of color does not negatively affect luminance contrast perception (<a href="https://pubmed.ncbi.nlm.nih.gov/24103453/" title="Achromatic luminance contrast sensitivity in X-linked color-deficient observers: an addition to the debate">Márta Janáky et al., 2013</a>; <a href="https://link.springer.com/article/10.1007/s10792-018-0881-7" title="Contrast sensitivity of patients with congenital color vision deficiency">Cagri Ilhan et al., 2018</a>). + Further, the inability to distinguish certain shades of color does not negatively affect contrast perception (<a href="https://pubmed.ncbi.nlm.nih.gov/24103453/" title="Achromatic luminance contrast sensitivity in X-linked color-deficient observers: an addition to the debate">Márta Janáky et al., 2013</a>; <a href="https://link.springer.com/article/10.1007/s10792-018-0881-7" title="Contrast sensitivity of patients with congenital color vision deficiency">Cagri Ilhan et al., 2018</a>). — Reply to this email directly, view it on GitHub <#3284 (review)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ACNGDXXAAZAB6HHKCC5SZCLXWSZQJANCNFSM6AAAAAA2K5JVDI>. You are receiving this because you were mentioned.

[bruce-usab]

@mbgower I concur with all your edits. But I am not clear if that means I should be clicking "resolved conversation" or not. That caused trouble last time I tried to use the feature.

1. On the call/survey you noted that recent changes were duplicative of some sentences further down the page. I did not track that observation, but maybe delete the redundant parts? Seems like lightweight noncontroversial editorial.
2. Also on the call/survey you noted that the in-line references (and hyperlinks) was a unique treatment. I agree. But I do not think they belong in the "Related Resources". I considered adding new section, References, and listing the citations there. Do we have other Understanding docs with that sort of category grouping? This might be better addressed in a separate issue/PR.

[alastc]

I've accepted Michael's edits whcih resolves the conversations. I also added preview in the description.

[alastc]

2. Also on the call/survey you noted that the in-line references (and hyperlinks) was a unique treatment.  I agree.  But I do _not_ think they belong in the "Related Resources".  

Hi Bruce, are you sure? I applied that change (before reading this comment!) and it seems ok to me. In the resources listing it is easier to spell out the full title of the research. I don't think leaving it in the main text (with titles attributes for the title of the research!) is a good way of including them.

We could probably hack in some within-page (footer style) links to attach the resources to that place in the text.

[bruce-usab]

@alastc I am okay with whatever treatment for the citations.

I made them hypertext links because they were much more academic than any of our other "Related Resources" which tend to practical utility. AFAIK we do not elsewhere use links under Related Resources to justify specific assertions in Understanding.